Can you post more details about your device? Android version, model, and so on?
When it kicks you out of the game, does the application close, or is it just returning you to a home screen? Does it kick you out around the same time each time?
Hey, I just pushed out a hotfix that might solve your issue. There was a memory leak when opening the save select screen, which was already intensive enough due to the thumbnails. Try getting the new APK I just uploaded.
If you're still seeing issues, try deleting your previous saves (either through in-game or through file management) and trying again.
If that doesn't work, could you reach out to me on Twitter @JosephOPossum or email josephopossum@gmail.com so we can get to the bottom of this? Thanks for your help and patience!